1. Field of Invention
The invention relates to, in general, a connection system and, in particular, one for establishing an electrical connection between an electrical device for the automotive industry and at least one pair of cables. The invention is advantageously applied to an, electrical-traction vehicle and, in particular, a hybrid vehicle for establishing an electrical connection between an electronic-control unit and a rotating electrical machine by a tern of cables.
2. Description of Related Art
Electrical traction combined with traditional thermal traction for making hybrid traction is becoming increasingly more popular in road vehicles. Electrical traction generally includes the use of a three-phase (typically synchronous of the “permanent magnet” type) reversible-rotating electrical machine (i.e., that may work as either an electrical motor drawing electricity and generating a mechanical motive torque or electrical generator drawing mechanical energy and generating electricity) one side of which is mechanically connected or connectable to the drive wheels and the other side of which is electrically connected to an electronic-control unit (containing an electronic-power converter). The connection between the rotating electrical machine and electronic-control unit occurs by three cables that are nominally flexible, but that, in fact, have a rather limited flexibility due to their large cross-sectional area (in the order of about 50-70 mm2 each) and external electromagnetic-interference shielding.
On one end, each cable is fixed to a corresponding terminal of the rotating electrical machine, and, on the other end, each cable is fixed to a corresponding terminal of the electronic-control unit. Generally, each cable is connected to the terminal of the rotating electrical machine at the time of construction of the rotating electrical machine (with the rotating electrical machine off the vehicle and wide possibilities of working about the rotating electrical machine itself). Thus, the connection between each cable and the terminal of the rotating electrical machine is simple and quick to establish even if the flexibility of the cables is relatively limited. Instead, each cable is connected to the terminal of the electronic-control unit aboard the vehicle when both the electronic-control unit and rotating electrical machine are already installed in their respective final positions (when the electronic-control unit is not very accessible and with little freedom of movement. Consequently, the connection between each cable and the terminal of the electronic-control unit is complex and hardworking.
Currently, each cable ends with an eyelet terminal that must be inserted, one at a time, about a connection screw of a corresponding terminal of the electronic-control unit, the eyelet connection being fixed to the connection screw by a nut coupled to one washer or more washers. Such a connection method is cost-effective and reliable (i.e., does not separate over time, by effect of vibrations), but, on the contrary, also rather complex and hardworking to implement due to (as explained above) the reduced accessibility to the electronic-control unit.
To make the “connection” operation simpler, it has been suggested to apply male connectors to the cables and corresponding female connectors to the electronic-control unit. In this manner, the male connectors of the cables are simply inserted in the corresponding female connectors of the electronic-control unit to establish the connection. However, this solution is much more costly (due to the high cost of the connectors) and less reliable because the prolonged vibrations of the vehicle may determine a separation (also only partial) between a male connector and the corresponding female connector.
Thus, there is a need in the related art for a connection system for establishing an electrical connection between an electrical device for the automotive industry and at least one pair of cables. More specifically, there is a need in the related art for such a connection system that is free from the drawbacks described above and, at the same time, simple and cost-effective to establish.